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Phage therapy by oral administration requires enhanced resistance of phages to the harsh gastric conditions. The aim of this work is the microencapsulation of phages in natural biopolymeric matrices as a protective barrier against the gastric environment. Alginate and pectin are used as base polymers. Further emulsification with oleic acid or coating with a different biopolymer is also studied. Emulsified pectin shows the maximum encapsulation efficiency and the highest protection against acidity, leaving more than 10(3) active phages after 30 min exposure at pH = 1.6, and protects phage from pepsin activity (4.2 mg mL(-1)). Non-encapsulated phages are fully inactivated at pH = 1.6 or with pepsin (0.5 mg mL(-1)) after 10 min.

Pectins (Pec) of 33 to 74 % esterification degree were tested with doxorubicin (Dox), a very high toxic drug widely used in cancer therapies. Pec with 35 and 55 % DE were selected because of the Dox binding higher than Pec microspheres of 35 and 55 % obtained by ionotropic gelation with Ca+2 have 88 and 66 % Dox loading capacity. Kinetic Dox release showed more than 80.0 and about 30.0 % free drug from 35 % and 55 % Pec formulations at pH 7.4, and 37 °C after 1-h incubation, respectively. Besides, Dox release decrease to 12 % in 55 % Pec microsphere formulation after 1-year storage at 4 °C. FTIR analysis of Pec–Dox complex showed hipsochromic shifts for the σC0O, δN-H and σC-C vibrational modes compared to Dox spectrum suggesting strong interaction between the drug cargo and the matrix. Rheological studies of Pec and Pec–Dox samples flow behavior exhibited a shear-thinning nature. Fifty-five percent of Pec showed higher viscosity than the viscosity for 35 % Pec in all range of temperatures analyzed, and decreased when the temperature is raised. Besides, Pec–Dox complexes have higher viscosity values than those of the corresponding Pec samples, and viscosity curves as function of shear rate for 35 % Pec–Dox are above the curves of 55 % Pec–Dox. In both cases, the results are confirming significant interaction between the cargo and the matrix, which also was established in viscoelastic dynamic analysis., Centro de Investigación y Desarrollo en Fermentaciones Industriales, Centro de Investigación y Desarrollo en Ciencias Aplicadas

The release of enrofloxacin entrapped in polyvinyl alcohol (PVA) cryogel at pH 5.5 showed a first-order kinetic, releasing 69.7% of the antibiotic after 4.5 h at 37 °C. In order to slow down the fluoroquinolone release rate, high-methoxylated pectin was added into the cryogel (PVA–P). A film containing 1.0% (w/v) HM pectin and 5.0 μg/ml enrofloxacin released only 3.7% of the antibiotic after 4.5 h. Since the FTIR spectrum showed that most of the interactions between PVA–P matrix and enrofloxacin were due to polar groups (carboxylate and amine), a two-layer film system was designed to modulate the releasing rate of the drug. The top film equilibrated with 0.75 or 1.5 M NaCl release up to 41.9% and 89.0% of the enrofloxacin in 4 h, respectively. The release rate of enrofloxacin was found dependent on NaCl concentration in the upper gel layer. The two-layer cryogel system showed attractive features for transcutaneous antibiotic delivery., Centro de Investigación y Desarrollo en Fermentaciones Industriales

An organic solvent-tolerant lipase from olive oil-induced Aspergillus niger MYA 135 supernatant was purified using two methods: electroelution and ion-exchange chromatography. With electroelution purification was 8.4-fold and recovery 47% and with ion-exchange 16.6-fold and 53.4%, respectively. The purified enzyme showed a prominent single band with SDS-PAGE and was a monomeric protein of 68 kDa. The isoelectric point (pI) of the lipase was 5.1 and optimum pH and temperature for activity were 7.0 and 37 °C, respectively. The lipase showed affinity for esters with long acyl chains, with a K m of 0.99 mM for C18. Substrate specificity of the immobilized lipase was highest for C18 among the various α- and β-naphthyl esters assayed. Substrate specificity agreed with kinetics parameters of long-chain fatty acids (C18). Transesterification activity of the A. niger MYA 135 lipase indicates that it could be a potential biocatalyst for biodiesel production.

New carboxylesterase from organic-solvent-tolerant Bacillus licheniformis S-86 strain was characterized. The enzyme named as type II esterase showed an optimal activity in the temperature range 60–65 °C and pH 8.0. The enzyme was moderatly thermostable (half-life of 1 h at 50 °C), but remarkable stable at extremely alkaline pH, retaining 100% of its activity at pH 10.0–11.0. Furthermore, the esterase showed high stability in detergents (86% residual activity in 10% SDS), and also 0.1% ionic and non-ionic detergents are inducers of enzyme activity. PMSF, a serine protease inhibitor, did not show any effect on the activity. The immobilized type II esterase was able to synthesize isoamyl acetate from isoamyl alcohol and p-nitrophenyl acetate (acyl donor) in n-hexane. The resulting ester yield (42.8%), obtained at a low temperature (28 °C) and with a very low amount of enzyme (4.6 × 10−5 mg ml−1), indicates a high potential for type II esterase in isoamyl acetate synthesis for production purposes. Fil: Torres, Sebastián. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; Argentina Fil: Baigori, Mario Domingo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; Argentina Fil: Swathy, S. L.. Indian Institute of Technology; India Fil: Ashok Pandey. Indian Institute of Technology; India Fil: Castro, Guillermo Raul. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Fermentaciones Industriales. Universidad Nacional de la Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Fermentaciones Industriales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; Argentina. Tufts University; Estados Unidos

New thermophilic and organic-solvent-tolerant Bacillus licheniformis S-86 strain is able to produce two active and solvent-stable esterases. Production of type I and II esterases was substantially enhanced when oils and surfactants were supplied as carbon sources. Grape oil (0.1% v/v) and Tween 20 to 60 (0.1% v/v) had enhanced enzyme production between 1.6- and 2.2-folds. Type II esterase was purified to homogeneity in a five-step procedure. This esterase was purified 76.7-fold with a specific activity of 135 U mg(-1). Molecular mass of the enzyme was estimated to be 38.4 kDa by sodium dodecyl sulfate polyacrylamide gel electrophoresis. Type II esterase was active mostly on esters with short acyl chains, which allowed to classify the enzyme as a carboxylesterase with a K (m) of 80.2 mmol l(-1) and a V (max) of 256.4 micromol min(-1) mg(-1) for p-nitrophenyl acetate. Also, B. licheniformis S-86 type II esterase displayed activity in presence of water-miscible organic solvents at 50% concentration and stability after 1-h incubation. Fil: Torres, Sebastián. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; Argentina Fil: Baigori, Mario Domingo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; Argentina Fil: Ashok Pandey. Indian Institute of Technology; India Fil: Castro, Guillermo Raul. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Fermentaciones Industriales. Universidad Nacional de la Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Fermentaciones Industriales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; Argentina. Tufts University; Estados Unidos

Six pectins with 35% to 91% methoxylation degree were purified and characterized to encapsulate Crystal Violet (CV). Amidated low methoxylated pectin (ALMP) was selected based on microsphere morphologies, aqueous solubility, viscosity and the effect of calcium concentration. Pectin microspheres were stabilized with Arabic gum (AG) and optimized according to the loading. Microspheres composed of 2.0% ALMP-1.0% AG crosslinked with 450mMcalcium(II)were able to encapsulate 217±2 μMCV. Opticalmicroscopy of the gels revealed spheroid microspheres with 250 ± 50 μm diameter containing homogenous CV distribution. Dried microspheres observed by SEM and epifluorescence showed a highly shrinkable matrix keeping the spheroidal morphology. Low relative viscosity of the ALMP-AG-CV solutions was found compared to ALMP and ALMP-AG. The Young moduli (60–80 Pa) of ALMP-AG microspheres by texturometric analysis indicated that the CV could interfere with the gel crosslinking. Raman spectroscopy analysis suggested some interaction of CV nucleophilic center within the matrix. FTIR of the matrix showed largest shifts in the carbonyl and carboxylate groups probably associated to H-bridges. CV stability studies performed on ALMP-AG microspheres, synthetized from polymer solutions with pH values above and below pectin pKa and showed faster CV release rates in presence of ionic strength., Centro de Investigación y Desarrollo en Tecnología de Pinturas, Centro de Química Inorgánica, Centro de Investigación y Desarrollo en Criotecnología de Alimentos, Centro de Investigación y Desarrollo en Fermentaciones Industriales

Bacillus amyloliquefaciens MIR-41 produces three exocellular amylolytic enzymes: α-amylase, pullulanase and α-glucosidase. Physicochemical factors such as pH and/or temperature may affect the enzyme yield. Continuous culture at a dilution rate of 0.15 h -1 demonstrated that the maximum production of α-amylase and α-glucosidase occurred at 36 o C and pH 6.8 and of pullulanase at 44 o C and pH 5.6. The results indicated that combinations of temperature and pH might be used for the production of crude extracts of α-amylase or pullulanase

Bacillus arnyloliquefaciens MIR-41 has been isolated from natural sources and characterized using statistical methods. The strain showed three types of glucanase activities : a-amylase, a-glucosidase and pullulanase in defined medium and starch as carbon source. Extracellular activity of a-amylase was approximately three times higher in continuous culture than in batch. Maximal productivity was found at a dilution rate of 016 h-l. Alpha-glucosidase was expressed as a cell-bound enzyme in batch culture, but in continuous culture was mostly extracellular. Pullulanase was cell-bound in all cases. The expression of the enzymes was dependent upon the system and the dilution rate used. No cell lysis was detected in the chemostat as compared with batch cultures.

Pectin was used as nucleation agent in the synthesis of spherical mesoporous Ag3PO4 microspheres for the development of dual antimicrobial carrier containing a fluoroquinolone. The hybrid Ag3PO4-pectin microspheres were characterized by biophysical methods using optical, scanning and transmission electronic microscopies, X-ray diffraction and energy dispersive analysis, differential scanning calorimetry, laser diffraction, and molecular gas adsorption (BrunauereEmmetteTeller). Scanning electron microscopy (SEM) images of silver phosphate microspheres without pectin displayed heterogeneous surface, bimodal size distribution between 0.9-1.0 mm and 1.5-1.8 mm with 20% and 25% population yield respectively and high amount of salt detritus. Meanwhile, SEM microphotographies of silver phosphate microspheres synthesized in presence of pectin showed a drastic change of particle morphology, homogenous surface, narrow size particle distribution in the 1.3-1.5 mm range with 90% population yield, 20-30% pore size increase and without debris. X-ray diffraction analysis of silver phosphate microspheres showed the same crystal profile in presence or absence of pectin suggesting no changes in the crystalline structure of Ag3PO4 by the addition of the biopolymer was made. Effect of silver phosphate hybrid microspheres loaded with levofloxacin tested against Escherichia coli and Staphylococcus aureus showed strong bactericidal activity compared with the bacteriostatic effect of free levofloxacin. The results are suggesting that hybrid Ag3PO4epectin microspheres containing levofloxacin can be used as effective antimicrobial against several microorganisms, making them applicable to diverse medical devices and for antimicrobial control systems. The Ag3PO4-pectin hybrid microspheres are advantageous since they are synthesized by green chemistry methodology under standard laboratory conditions, do not requiring purification steps, the technique is highly reproducible and they are available for drug loading and specific target tailoring. The main advantage of Ag3PO4-pectin microspheres is the synergic antimicrobial activity of the silver ion and the antibiotic in the same microdevice acting as biocide matrix and also as carrier for levofloxacin.. Fil: Bayon, Bernardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Fermentaciones Industriales. Universidad Nacional de la Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Fermentaciones Industriales; Argentina Fil: Bucala, Veronica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; Argentina Fil: Castro, Guillermo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Fermentaciones Industriales. Universidad Nacional de la Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Fermentaciones Industriales; Argentina

Bacterial cellulose (BC) is an extracellular polymer produced by many microorganisms. The Komagataeibacter genus is the best producer using semi-synthetic media and agricultural wastes. The main advantages of BC are the nanoporous structure, high water content and free hydroxyl groups. Modification of BC can be made by two strategies: in-situ, during the BC production, and ex-situ after BC purification. In bioprocesses, multilayer BC nanocomposites can contain biocatalysts designed to be suitable for outside to inside cell activities. These nanocomposites biocatalysts can (i) increase productivity in bioreactors and bioprocessing, (ii) provide cell activities does not possess without DNA cloning and (iii) provide novel nano-carriers for cell inside activity and bioprocessing. In nanomedicine, BC matrices containing therapeutic molecules can be used for pathologies like skin burns, and implantable therapeutic devices. In nanoelectronics, semiconductors BC-based using salts and synthetic polymers brings novel films showing excellent optical and photochemical properties. Fil: Cacicedo, Maximiliano Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Fermentaciones Industriales. Universidad Nacional de la Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Fermentaciones Industriales; Argentina Fil: Castro, M. Cristina. Universidad Pontificia Bolivariana; Colombia Fil: Servetas, Ioannis. University of Patras; Grecia Fil: Bosnea, Loulouda. University of Patras; Grecia Fil: Boura, Konstantina. University of Patras; Grecia Fil: Tsafrakidou, Panagiota. University of Patras; Grecia Fil: Dima, Agapi. University of Patras; Grecia Fil: Terpou, Antonia. University of Patras; Grecia Fil: Koutinas, Athanasios. University of Patras; Grecia Fil: Castro, Guillermo Raul. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Fermentaciones Industriales. Universidad Nacional de la Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Fermentaciones Industriales; Argentina

In recent years, there has been a strong focus on beneficial foods with probiotic microorganisms and functional organic substances. In this context, there is an increasing interest in the commercial use of kefir, since it can be marketed as a natural beverage that has health promoting bacteria. There are numerous commercially available kefir based-products. Kefir may act as a matrix in the effective delivery of probiotic microorganisms in different types of products. Also, the presence of kefir's exopolysaccharides, known as kefiran, which has biological activity, certainly adds value to products. Kefiran can also be used separately in other food products and as a coating film for various food and pharmaceutical products. This article aims to update the information about kefir and its microbiological composition, biological activity of the kefir's microflora and the importance of kefiran as a beneficial health substance., Facultad de Ciencias Exactas

Bacterial cellulose (BC) films modified by the in situ method with the addition of alginate (Alg) during the microbial cultivation of Gluconacetobacter hansenii under static conditions increased the loading of doxorubicin by at least three times. Biophysical analysis of BC-Alg films by scanning electron microscopy, thermogravimetry, X-ray diffraction and FTIR showed a highly homogeneous interpenetrated network scaffold without changes in the BC crystalline structure but with an increased amorphous phase. The main molecular interactions determined by FTIR between both biopolymers clearly suggest high compatibility. These results indicate that alginate plays a key role in the biophysical properties of the hybrid BC matrix. BC-Alg scaffold analysis by nitrogen adsorption isotherms revealed by the Brunauer?Emmett?Teller (BET) method an increase in surface area of about 84% and in pore volume of more than 200%. The Barrett?Joyner?Halenda (BJH) model also showed an increase of about 25% in the pore size compared to the BC film.Loading BC-Alg scaffolds with different amounts of doxorubicin decreased the cell viability of HT-29 human colorectal adenocarcinoma cell line compared to the free Dox from around 95?53% after 24 h and from 63% to 37% after 48 h. Dox kinetic release from the BC-Alg nanocomposite displayed hyperbolic curves related to the different amounts of drug payload and was stable for at least 14 days. The results of the BC-Alg nanocomposites show a promissory potential for anticancer therapies of solid tumors., Centro de Investigación y Desarrollo en Fermentaciones Industriales, Centro de Química Inorgánica

Gamma-hexachlorocyclohexane (γ-HCH or lindane), one of the most commonly used pesticides, has been mainly used in agriculture; this pesticide is known to be highly toxic and persistent, causing serious water and soil contamination. The objective of the present work is to study the effect of low glucose concentration and the addition of lindane at different growing time on the pesticide detoxification ability of Streptomyces M7. After 96 h of incubation in synthetic medium containing glucose 0.6 g l–1 with the addition of lindane 100 μg l–1 at 20 h of incubation, a typical diauxic curve was obtained: glucose was the preferred substrate until 24 h, at 48 h, when the carbohydrate was depleted, the microorganism consumed the pesticide like carbon source. On the other hand, lindane removal induction was observed, which was greater when the pesticide was added to the medium at 20 h than 6 h of incubation. Between 72 and 96 h, a maximum of ∼86% of the Cl– was released when lindane was added to the medium at 20 h, whereas ∼70% and 67% Cl– was released in the medium when the pesticide was added at 0 and 6 h of incubation respectively. This is the first report of chloride release from inoculated medium supplemented with lindane, suggesting that the pesticide was degraded by Streptomyces sp. under aerobic conditions. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Thermoresistant and alcohol-tolerant bacterium Bacillus licheniformis S-86 can produce a stable esterase in high organic solvents concentrations. In this work, the effects of seven alkanols on cell growth, sporulation, and esterase production of Bacillus licheniformis S-86 were investigated. A reciprocal relationship between maximal organic solvent concentrations tested with log P was observed but there was no correlation between the alcohol log P and the esterase production. Esterase specific activity was approximately two-fold higher in cultures supplemented with C3–C5 alkanols than the control. The addition of 3-methylbutan-1-ol to the culture medium, strongly depleted sporulation compared to the control by 104-fold CFU/ml; but, the esterase production was enhanced more than two times under the same conditions.

Biocatalysis-based technologies are becoming a burgeoning arena of research and industrial applications since the need of intensive use of natural resources with reduced pollution is now a world trend. The advance of Green Chemistry is based on the major development of many areas of the scientific knowledge which involves from the detection of enzyme molecular intermediates and products at very low concentrations, to the development of the biocatalyst ready for the challenge of industrial processes via several strategies such as enzyme immobilization, changes of protein structure, genetic databases, to tailoring the reaction media and raw material processing. In the present chapter, some fundamental topics of biocatalysis will be analyzed in terms of present and future applications at large scale.

Phosphatidylinositol-specific phospholipase C (PI-PLC) activity was investigated in 25 different lactic acid bacteria (LAB) strains belonging to the genera Lactobacillus, Weisella, and Enterococcus. PI-PLC activity was detected in 44% of the strains studied in culture medium without carbon source. From the PI-PLC positive strains, Lactobacillus rhamnosus ATCC 7469 was selected for translocation studies. Healthy mice were orally administered with a daily dose of 2.0U109 of viable L. rhamnosus suspension. Viable bacteria were detected in liver and spleen of mice fed with LAB for 7 days. Bacterial colonies isolated from liver were biochemically characterized, and further subjected to randomly amplified polymorphic DNA. Amplification patterns of five strains displayed identical profiles to L. rhamnosus. PI-PLC activity was determined in the strains recovered from liver. Fil: Rodriguez, Ana Virginia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; Argentina Fil: Baigori, Mario Domingo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; Argentina Fil: Alvarez, Gladis Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; Argentina Fil: Castro, Guillermo Raul. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; Argentina Fil: Oliver, Guillermo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; Argentina

Strain desinganted R22 and R25, isolated from Sali River sediments, Argentina, were highly resistant to chromium. these strains were shown by 16S rRNA sequencing studies to be Streptomyces spp.; this affiliation was consistent with morphological and chemical characteristics. Growth of R22 and R25 in medium containing 100 mg/l chromate was reduced by only 23% and 34%, respectively, compared with growth in medium without added chromium. Streptomyces sp. strains R22 and R25 both accumulated chromium with yields of 10.0 and 5.6 mg Cr/g of dry weight, respectively, and chromate concentration of 50 mg/ml. Cell fractionation studies with strain R22 showed that the great majority of the chromium were associated with the cell wall fraction. Streptomyces R22 and R25 may have applications in bioremediation of chromium contamination. Fil: Amoroso, Maria Julia del R.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; Argentina. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Microbiología; Argentina Fil: Castro, Guillermo Raul. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; Argentina Fil: Duran, A.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Tecnología Agroindustrial del Noroeste Argentino. Provincia de Tucumán. Ministerio de Desarrollo Productivo. Estación Experimental Agroindustrial ; Argentina Fil: Peraud, O.. University of Maryland; Estados Unidos Fil: Oliver, G.. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Microbiología; Argentina Fil: Hill, R. T.. University of Maryland; Estados Unidos

UV scanning of a-chymotrypsin dissolved in neat glycerol and water showed no significant differences in its spectra at pH 7.8. Fluorescence scanning revealed a strong dependence on pH values (between 5.9 to 10.5) of the maximum wavelength emission in water and no pH-dependence in 99% glycerol supplemented with 1% of appropriate buffers. The profile of a-chymotrypsin activity dissolved in water-glycerol mixtures with phenyl acetate as substrate displayed two maximum: highest peak was found at 100% water, and the second one was observed in 99% glycerol concentration with about 40% of the relative activity. Optimum pH of the soluble a-chymotrypsin in glycerol showed a displacement of 1 pH/U towards the alkaline side compared to water at pH 8.0. Kinetic and thermodynamic analysis using kinetic measurements of the thermal stability of a-chymotrypsin showed a higher inactivation rate in neat glycerol as compared to water in 30 to 45°C range, however, when temperature increases enzyme stability in glycerol is better than water. Thermostability of trypsin and a-chymotrypsin dissolved in glycerol at 100°C showed a half reaction time of approximately 7 and 20 h, respectively, and less than 1 minute in aqueous buffer for both enzymes. Fil: Castro, Guillermo Raul. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; Argentina. Massachusetts Institute of Technology; Estados Unidos

In 6 of 14 neat organic solvents enzymatic activity of dissolved subtilisin was detected. Subtilisin showed approximately 500× higher activity in glycerol than in ethylene glycol, N -methylacetamide, N -methylformamide, 1,2- and 1,3-propanediol. Comparison of soluble proteases in glycerol shows that subtilisin has between 16 to 44× higher V m , and the same K m range compared with chymotrypsin, thermolysin, and trypsin using phenyl acetate as a substrate at 30°C. However, the K m of subtilisin in glycerol was 10× higher than in water. Autolysis rate of subtilisin in glycerol at 30°C is about 3.5× lower than in water, and the rate of autolysis increases from 2.6 to 9× in glycerol and from 44× in water at 37 and 45°C, respectively. Changes in the specificity of bovine serum albumin cleavage by subtilisin were observed by switching from homogeneous glycerol solution to aqueous medium: BSA fragments with different molecular masses in the range of 20 and 40 kDa, and different intensity peaks were detected by using chromatography (fast protein liquid chromatography) and mass spectrometry (matrix-assisted laser desorption ionization-time of flight) techniques.

An acid α-amylase hyperproducing strain, designated as MIR-61, was isolated in a screening procedure from South American soil samples. MIR-61, a 60°C thermoresistant strain, was identified using 98 biochemical and morphological tests and characterized as Bacillus licheniformis by numerical taxonomy. Batch cultures of B. licheniformis MIR-61 showed extracellular α-amylase and α-glucosidase activities during the exponential growth phase. The production of α-amylase was studied at free and constant pH values at 37 and 45°C. Maximum α-amylase activity (4,767 kU/dm3 in a liquid medium) was detected at 45°C at a constant pH (7.0) in the late exponential phase. The α-amylase production by B. licheniformis MIR-61 is 10 to 300 times higher than the enzyme production reported in strains of the same species. Optimum α-amylase activity was found at 50 to 67°C in an acid pH range from 5.5 to 6.0. These properties would allow its use in starch industry processes.

β-1,4-Xylanase, produced extracellularly by Bacillus amyloliquefaciens MIR 32, was isolated directly from the culture broth by adsorption on a cation exchanger, Amberlite IRC-50, in fluidized bed with a low degree of expansion. The enzyme was eluted from the adsorbent by increase in pH, with a recovery of 82.3% and purification of 5.3 fold. About 99.99% of the colony forming units, 82% of the contaminating neutral protease activity, and 100% of the reducing sugars present in the crude feedstock were removed at the end of the purification cycle.

Mixed cultures of Bacillus amyloliquefaciens MIR-41 and Zymomonas mobilis Flo-B3 showed a 2.5 fold increase in α-amylase production, and a 20 times fold decrease in ethanol production compared with pure cultures. Enhanced α-amylase production by B. amyloliquefaciens in mixed cultures after 24 h could be attributed to the lack of repression in the synthesis of α-amylase by ethanol and protease inhibition by the pH of the culture medium.

A Bacillus amyloliquefaciens strain isolated from soil produced xylanolytic enzymes in the extracellular medium when grown on xylan and nitrate. No cellulase activity was detected. Xylanase was purified from the culture supernatant in three steps which comprised anion-exchange adsorption, ammonium sulfate precipitation, and hydrophobic interaction chromatography. The pure enzyme appeared as two close protein bands on SDS-PAGE with molecular weights of 18.4 and 19.6 kD, respectively. The molecular weight obtained by sedimentation equilibrium under native conditions was about 18.5 kD. The isoelectric point was 10.1. The enzyme contains a relatively high content of aspartate, glycine, and threonine. Tryptophan seems to be essential for xylanase activity. The presence of carbohydrate was noted in the pure enzyme. Circular dichroism studies indicated that the protein contains almost equal proportions of α-helix, β-sheet, and β-turns. The optimum pH of activity was 6.8–7.0. The enzyme exhibited good stability even at pH 9.0. Excellent stability was observed at 50°C even though optimal activity was at 80°C. The activity was completely inhibited by Hg 2+ ions and was reduced drastically in the presence of Cu 2+ and Fe 3+ ions. Mn 2+ ions, EDTA, β-mercaptoethanol, and dithiothreitol up to 5 m m stimulated the enzyme activity.

Fifty-three strains of actinomycetes resistant to heavy metals were isolated from the Salí River in northwest Argentina. Screening procedures that involve solid and liquid synthetic media containing Cd(2+), Cu(2+), or Hg(2+) allowed the selection of six strains. These strains showed a quantitative sorption of Cd(2+) and Cu(2+) by more than 98% of the initial metal concentrations (0.1, 0.5, and 1.0 mM) tested.

α-l-Rhamnosidase (E.C. 3.2.1.40) from Brevundimonas sp. Ci19 was immobilized as a cross-linked enzyme aggregate (CLEA) via precipitation with acetone followed by glutaraldehyde cross-linking. The effects of precipitation and cross-linking on CLEA activity were investigated and characterized. Sixty percent acetone solution and 2.0 % glutaraldehyde were used at pH 7.0 for 1-h cross-linking reaction. The yield of rhamnosidase-CLEA was approximately 80 % starting from crude extracts or pure enzyme suggesting non-purification steps are required for extended use. No significant differences in optimum pH and temperature values of the enzyme were recorded after immobilization. The rham-CLEA recycled 4 times showed about 80 % rhamnosidase activity; meanwhile, in the fifth and six recycled time, the enzyme activity was reduced to about 40 and 20 %, respectively., Centro de Investigación y Desarrollo en Fermentaciones Industriales

Alginate lyase (AL) from Sphingobacterium multivorum is unsuitable for oral delivery because of its rapid inactivation under acidic conditions. The synthesis of a novel crosslinking enzyme aggregate (CLEA) of AL (AL-CLEA) is proposed. AL precipitation with 95% ammonium sulfate and combined with low methoxylated pectin (LMP), showed 100% precipitation yield. Crosslinking with glutaraldehyde reduced the AL-CLEA activity to less than 1%, but addition of bovine serum albumin (BSA) and LMP during AL-CLEA synthesis increased the activity yield to 14.7%. AL-CLEA exposed to simulated gastric conditions (pH 1.2 to 3.0) showed more than 70% retention of enzymatic activity. Moreover, AL-CLEA showed thermal stability at temperatures over 37 °C. Stability against chemical denaturants (ethanol, acetone and propylene glycol) showed that AL-CLEA was 14 times more stable than free AL in all cases. Finally, a 25% viscosity reduction of alginate solution was achieved with AL-CLEA. This is the first report of AL-CLEA synthesis and evaluation. Fil: Islan, German Abel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - la Plata. Centro de Investigación y Desarrollo En Fermentaciones Industriales. Universidad Nacional de la Plata. Facultad de Cs.exactas. Centro de Investigación y Desarrollo En Fermentaciones Industriales; Argentina Fil: Martinez, Nelida Yanina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - la Plata. Centro de Investigación y Desarrollo En Fermentaciones Industriales. Universidad Nacional de la Plata. Facultad de Cs.exactas. Centro de Investigación y Desarrollo En Fermentaciones Industriales; Argentina Fil: Illanes, Andres. Pontificia Universidad Catolica de Valparaiso; Chile Fil: Castro, Guillermo Raul. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - la Plata. Centro de Investigación y Desarrollo En Fermentaciones Industriales. Universidad Nacional de la Plata. Facultad de Cs.exactas. Centro de Investigación y Desarrollo En Fermentaciones Industriales; Argentina

Doxorubicin (Dox) is a hydrophilic drug extensively used for treatment of breast, lung, and ovarian cancer, among others; it is highly toxic and can cause serious side effects on nontargeted tissues. We developed and studied a hybrid nanoporous microparticle (hNP) carrier based on calcium carbonate and biopolymers derivatized with folic acid (FA) and containing Dox as a chemotherapeutic drug model. The hNPs were characterized by X-ray diffraction, and Raman and Fourier transform infrared (FTIR) spectroscopies. The X-ray diffraction patterns of calcium carbonate particles showed about 30–70% vaterite–calcite polymorphisms and up to 95% vaterite, depending on the absence or the presence of biopolymers as well as their type. Scanning electron microcopy images revealed that all types of hNPs were approximately spherical and porous with average diameter 1–5 μm, and smaller than CaCO3 microparticles. The presence of biopolymers in the matrices was confirmed after derivatization with a fluorescein isothiocyanate probe by means of confocal microscopy and FTIR synchrotron beamline analysis. In addition, the coupling of lambda carrageenan (λ-Car) to FA in the microparticles (FA–λ-Car-hNPs) increased the cancer-cell targeting and also extended the specific surface area by up to ninefold (26.6 m2 g−1), as determined by the Brunauer–Emmett–Teller isotherm. A nanostructured porous surface was found in all instances, and the FA–λ-Car-hNP pore size was about 30 nm, as calculated by means of the Barrett–Joyner–Halenda adsorption average. The test of FA–λ-Car-hNP anticancer activity on human osteosarcoma MG-63 cell line showed cell viabilities of 13% and 100% with and without Dox, respectively, as determined by crystal violet staining after 24 h of incubation. Fil: Bosio, Valeria Elizabeth. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - la Plata. Centro de Investigación y Desarrollo En Fermentaciones Industriales. Universidad Nacional de la Plata. Facultad de Cs.exactas. Centro de Investigación y Desarrollo En Fermentaciones Industriales; Argentina Fil: Cacicedo, Maximiliano Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - la Plata. Centro de Investigación y Desarrollo En Fermentaciones Industriales. Universidad Nacional de la Plata. Facultad de Cs.exactas. Centro de Investigación y Desarrollo En Fermentaciones Industriales; Argentina Fil: Calvignac, Brice. Université d’Angers; Francia Fil: Leon, Ignacio Esteban. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - la Plata. Centro de Química Inorganica "dr. Pedro J. Aymonino". Universidad Nacional de la Plata. Facultad de Cs.exactas. Centro de Química Inorganica ; Argentina Fil: Beuvier, Thomas. Université du Maine; Francia Fil: Boury, Frank. Université d’Angers; Francia Fil: Castro, Guillermo Raul. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - la Plata. Centro de Investigación y Desarrollo En Fermentaciones Industriales. Universidad Nacional de la Plata. Facultad de Cs.exactas. Centro de Investigación y Desarrollo En Fermentaciones Industriales; Argentina

Doxorubicin (Dox) was co-encapsulated with congo red (CR) in order to increase drug encapsulation and sustain the release from gel microbeads composed of alginate–carboxy methyl guar gum (68/32) for oral controlled delivery. No release of either cargo molecule from the microbeads at pH 1.2 within 90 minutes was detected. However, 62% CR and 16% Dox were released from the gels at pH 7.4 at 37 °C in 8 hours when both the cargo molecules were studied alone. Presence of CR in the formulation reduces the release of Dox by about 25–30% under the same experimental conditions. Rheological properties of the formulations have been investigated at different temperatures between 20 and 37 °C. Shear thinning behavior was observed by steady-shear flow experiments for all formulations, and no yield stress was observed for any of the formulations. The temperature effect on Alg–CMGG–Dox–CR evidenced a synergic action between Dox and CR. Dynamic frequency sweep tests were performed to study the viscoelastic properties of the formulations. The patterns observed for Alg–CMGG indicated physical gel characteristics; however, all other formulations showed behaviour typical of concentrated solutions. These results confirm the interaction of Dox and CR, and the concomitant positive effect on sustainable release in oral delivery., Centro de Investigación y Desarrollo en Fermentaciones Industriales

The production of monoglycosylated flavonoids by α-l-rhamnosidases (EC 3.2.1.40) is an interesting development in biocatalysis. Applications of rhamnosidases in industry include removal of bitterness caused by naringin from citrus juices. In the present work, a psychrotolerant bacterial strain with α-l-rhamnosidase activity was isolated. The α-l-rhamnosidase was found to be able to degrade naringin and was purified and characterized. The α-l-rhamnosidase from Brevundimonas sp. Ci19 was able to release both rhamnose and prunin from naringin. The enzyme was partially purified with a performance of 2.7-fold purification. The α-l-rhamnosidase showed an optimum pH between 6.00 and 7.00 with substantial residual activity at pH 5.00 (85.3 %). The optimum temperature was between 20 and 37 °C. The enzyme showed activation in the presence of Ca2+ and Cd2+ ions and at a high ethanol concentration level (10 % v/v). Activity was found for β-d-glucosidase (EC 3.2.1.21) in the partially purified extract, but it was inactive in the acid pH region. This result indicates the potential for inactivation of β-d-glucosidase along with the high level of α-l-rhamnosidase activity necessary for the production of flavonoid glycosides. The α-l-rhamnosidase from Brevundimonas sp. Ci19 showed interesting properties for potential use not only in the citrus juice industry but also in winemaking., Centro de Investigación y Desarrollo en Fermentaciones Industriales

Background: In the past decade, considerable attention has been paid for the development of novel strategies for the synthesis of different kind of nano-objects. Most of the current strategies are usually working by the use physical or chemical principles to develop a myriad of nano-objects with multiple applications. Main fields of nanotechnology applications range from catalysis, micro- and nanoelectronics (semiconductors, single electrons transistors), non-linear optic devices, photoelectrochemistry to biomedicine, diagnostics, foods and environment, chemical analysis and others. Results: Two main avenues for nanoparticles synthesis: cell-free extract and cell cultivation have been reported. The state of art of both biotechnological approaches for different type nanoparticles are reviewed in this work. Conclusions: Nanotechnology is a revolutionary field just at its onset, the trend in the next decades being its integration with the green chemistry approach. Several strategies involving exhaustive strain selection, cultivation modes, recombinant gene expression, metabolic engineering, protein re-design and re-engineering, and predictive modeling will allow to create nanobioreactors, a new nanobiotechnology arena with a high potential impact in many fields. Fil: Cauerhff, Ana. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Biotecnología Aplicada. Laboratorio de Nanobiomateriales; Argentina; Fil: Castro, Guillermo Raul. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Biotecnología Aplicada. Laboratorio de Nanobiomateriales; Argentina

A new formulation is described based on biopolymeric microspheres containing alginate lyase (AL) and ciprofloxacin (Cip) for sustainable oral delivery in CF patients. Alginate (ALG) and high-methoxyl pectin (HMP) are selected as the biopolymers to develop a composite matrix. ALG microspheres coated with HMP and ALG-HMP blend are gelled in water/organic solvents mixtures, obtaining Cip encapsulations from 46.0 to 100.0%. ALG-HMP shows a Cip sustainable release profile and is able to encapsulate 90.0% of AL, showing 76.0% enzyme activity after release under simulated intestinal conditions. The developed system is a promising delivery carrier to treat chronic infection of Pseudomonas aeruginosa and to reduce the viscoelasticity of the mucus accumulated into intestine of CF patients.

Bacillus licheniformis MIR 29 has been isolated and produces extracellular proteases. It is able to grow at temperatures up to 60 °C and at pH values up to 9.0. Casein was the best carbon source for production of a thermostable protease activity which, in some conditions, is 90% extracellular. The synthesis of alkaline protease is not constitutive; different levels of production were found with different carbon and nitrogen sources. Casein was thought to be an inducer of enzyme synthesis. The optimal pH and temperature of the enzyme activity were 12 °C and 60 °C, respectively. The enzyme was stable up to 60 °C in the absence of stabilizers. The protease activity was inhibited with phenylmethylsulphonyl fluoride, indicating a serine-protease activity. The proteolytic activity was lowered by molecules present in the culture supernatant, which include amino acids and peptides, indicating end-product inhibition. Electrophoresis assay on denaturating gels showed two bands with alkaline protease activity, in the 25 to 40-kDa molecular mass range.

A keratinase isolated from Paecilomyces lilacinus (LPS #876) was tested against proteins present in the skin but the high enzyme activity was detected on collagen. Keratinase was physically immobilized onto PVA–pectin cryogels and enzyme release was 20.8 ± 2.1%, 63.8 ± 0.2%, 41.5 ± 3.5% and 26.0 ± 3.5% in cryogels containing pectins with esterification degrees (DE) 33.0%, 55.0%, 62.7% and 71.7% respectively at 37 ºC after 3 h incubation. In presence of 0.75 M NaCl, the percentage of enzyme release changed to: 57.5 ± 1.5, 65.8 ± 3.8, 57.3 ± 0.2 and 34.0 ± 4.0 for the four pectins respectively. In-vitro studies of enrofloxacin release from PVA–pectin cryogels at pH close to the human skin (pH = 5.5) showed 15.0% free antibiotic following first order kinetic at 37 ºC after 5 h incubation. However, in the presence of keratinase only 6.9% of enrofloxacin was released under the same experimental conditions., Centro de Investigación y Desarrollo en Fermentaciones Industriales

A simple procedure is described for the screening and isolation of xylanolytic bacteria, able to degrade hemicellulose. Bagasse hemicellulose was purified, cross-linked with green dye for use as indicator, and used in a Petri dish assay for the determination of xylanolytic activity. Hydrolysis of the substrate causes the formation of transparent halos around bacterial colonies. The screening procedure was used to select thermoresistant bacteria. The four best isolates were characterized and classified as Bacillus species.

A plate assay based on radial diffusion on Petri dishes containing inulin dye labeled with Remazol Brilliant Blue as substrate provides a specific, reliable and rapid inulinase estimation. It is of potential use in the screening of inulin utilizing microorganisms in large numbers of natural samples. In a screening program for inulinolytic sporeformers, 186 isolates were found to degrade inulin as the sole carbon source. Two strains, named VIR 9 and VIR 64, showed high extracellular enzymatic activity compared with a reference strain of Bacillus subtilis MIR 430A.

α-Glucosidase was detected in four wild-type amylolytic production strains belonging to the Bacillus genus. The strains showed α-glucosidase activity in extracellular and membrane-bound fractions. Kinetic studies of the α-glucosidase synthesis in the batch cultures of four strains of the Bacillus genus showed two profiles : partially and totally growth-linked synthesis. The presence of different activities and production profiles of α-glucosidase in the strains at high or low glucose concentrations in the medium would indicate that α-glucosidase may have a role in the regulation of the metabolism of α-polysaccharides.

Screening of ciprofloxacin (Cip) with selected biopolymers brings about 90% antibiotic interactions with a coacervate composed of alginate/high metoxylated pectin in 2:1 ratio. Fourier transform infrared spectroscopy analysis provides information about the nature of this interaction, revealing ionic and hydrophobic patterns among the molecules. Alginate/high methoxylated pectin gel microspheres developed by ionic gelation encapsulates 46.8 ± 5.0% Cip. The gel matrix can release Cip in a sustained manner, releasing 42.7 ± 0.2% in 2 h under simulated stomach pH conditions, and 83.3 ± 1.1% Cip release in 80 mM phosphate at pH = 7.40 (intestinal). The increase of sodium chloride from 50 to 200 mM implies a Cip release from 69.0 ± 1.5% to 95.1 ± 3.6% respectively in 2 h. Scanning electron microscopy revealed the cohesive effect of HM pectin over alginate molecules on the microsphere surface. Those results guarantee all Cip contained in the alginate/HM pectin microspheres could be released in an established kinetic profile along the gastrointestinal tract, avoiding the Cip undesirable side effects during absorption., Facultad de Ciencias Exactas, Centro de Investigación y Desarrollo en Fermentaciones Industriales, Centro de Investigación y Desarrollo en Ciencias Aplicadas

Emulsan–alginate beads were prepared and challenged using bovine serum albumin (BSA) to assess adsorption in comparison to alginate beads. BSA binding to the emulsan–alginate beads was improved over the alginate bead controls and protein adsorption was less sensitive to changes in ionic strength. BSA adsorption between pH 8.5 and 5.3 in alginate beads was 2–3-times lower compared to the emulsan–alginate beads in the same pH range. BSA adsorption and kinetic constants were at least 2-times higher for the emulsan–alginate beads compared to the alginate controls based on the Langmuir adsorption model. To further explore the utility of these novel emulsan–alginate bead systems, complex cell-free supernatants from some pathogenic microorganisms were exposed to the emulsan–alginate beads and increased protein adsorption was found when compared to controls. These trends were also confirmed with α-hemolysin toxicity studies. The data suggest that the protein-binding capacity of emulsan–alginate beads exceeds alginate controls, attributable to the unique binding features of emulsan., Centro de Investigación y Desarrollo en Fermentaciones Industriales

During the last 30 years the scope of biocatalysis has been expanding due to the advances in several technological fields. Diverse techniques as structural enzyme improvement (e.g. protein engineering, direct evolution), engineering approaches (e.g. ionic liquids, supercritical fluids) and physical stabilization (e.g. immobilization, CLEAS) have been developed, which in combination are powerful tools to improve biotransformation and to synthesize new products. In the present work, recent advances in biocatalysis are reviewed., Centro de Investigación y Desarrollo en Fermentaciones Industriales

Sulfasalazine (SLZ) is a synthetic nonsteroidal anti-inflammatory drug used mainly for the treatment of an inflammatory bowel and other diseases. Two pectins with different methylation degrees were blended to synthesized gel microspheres by ionotropic gelation for SLZ encapsulation. The encapsulation efficiency was found to be around of 99% in all formulations tested. However, different SLZ release profiles related to the methylation degrees of pectin were observed. Mixture of low methylated (LM) and high methylated (HM) pectins in the presence of calcium(II) displayed the best microsphere morphologies among the formulations tested determined by optical and electronic microscopies. The percentage of drug release using a mixture of LM and HM pectins after 255 min in simulated gastric fluid (pH = 1.2), simulated intestinal fluid (pH = 6.8), and phosphate buffer (pH = 7.4) were 15.0%, 47.0%, and 52.2%, respectively., Centro de Investigación y Desarrollo en Fermentaciones Industriales

Self-assembled hybrid organo-silica sol-gel materials are rapidly expanding for newand novel applications. The microporous solid silica matrix was used as a carrier for the controlled release of ascorbic acid (AA), selected as cargo molecule. One-step synthesis procedure was optimized for the preparation of silica–molecule composites by using tetraethoxysilane and methyltrimethoxysilane as precursors. The hydrophobic silica xerogel matrices were characterized by Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction. Specific surface area and porosity parameters were determined by Brunauer-Emmett-Teller (BET) technique and the matrix surface morphology by scanning electron microscopy (SEM). The observed release pattern could be interesting for the development of AA-fortified food and for use in food packaging., Hibridni, organsko-silikatni sol-gel materijal sve se više primjenjuje u prehrambenoj industriji. Stoga je kao nosač za kontrolirano otpuštanje askorbinske kiseline upotrijebljen mikroporozni čvrsti silikatni matriks. Optimirana je jednostupanjska sinteza kojom su dobiveni silikatni kompoziti uz pomoć prekurzora: tetraetoksisilana i metiltrimetoksisilana. Matriksi su hidrofobnog silikagela okarakterizirani Fourier transformiranom infracrvenom spektroskopijom (FTIR) i difrakcijom X-zraka. Specifična površina i poroznost matriksa ispitane su Brunaer-Emmett-Teller (BET) metodom, dok su morfološka svojstva površine matriksa određena skenirajućim elektronskim mikroskopom (SEM). Utvrđeno je da se askorbinska kiselina ovako može upotrijebiti za proizvodnju hrane s dodanom vrijednošću, te za pakiranje prehrambenih proizvoda.

Wild-type strains of the genus Bacillus were screened for antimicrobial activity. Two strains exhibited antimicrobial activity against Micrococcus luteus and were identified as Bacillus polymyxa MIR-23 and Bacillus circulans MIR-13. Bacillus polymyxa MIR-23 was active against Escherichia coli, Pseudomonas aeruginosa and Aspergillus niger, whereas Bacillus circulans MIR-13 did not show activity against these microorganisms. Bacillus subtilis ATCC 6633 and B. polymyxa ATCC 10401 were used as standard antibiotic-producer strain and showed different antimicrobial profiles and yields from B. polymyxa MIR-23. The different antimicrobial profile of the two selected strains could possibly be used as a taxonomic marker.

515 microorganisms of the genus Bacillus which produce starch‐degrading enzymes were isolated from natural environments in the course of a screening programme. Treating the Bacillus strains on agar plates with iodine reagent for 30 seconds led to the selection of clones with increased amylolytic activity. This methods is very convenient for the screening of large numbers of amylolytic strains. Copyright © 1993 Akademie Verlag GmbH